Dynamo electric machine



Feb. 7, 1933. H. QWEICIHSEL 1,896,264

DYNAMO ELECTRIC MACHINE Filed Feb. 23, 1929 Inventor HANS w EICHSEL AttyPatented Feb. 7, 1933 UNITED STATES PATENT OFFICE HANS 'WEICHSEL, OF ST.LOUIS, MISSOURI, ASSIGNOB TO WAGNER ELECTRIC conro- BATION, OF ST.LOUIS, MISSOURI, A CORPORATION 01' DELAWARE mmmo mnc'rmc mom Applicationfiled February 28, 1889. Serial No. 342,070.

In repulsion-induction motors asusually constructed the operation ofthe-brush shifta s. through the contact whereby currents aring andPIOdilOBj dB faces of a shaft terioration of the bearing face as the'result of sparking. Also, in some. alternating cur-: rent machinesvoltages induced inth'e shaftmay be the source of ob'ectionablecurrentsthrough the bearing. e objectof my invention is toprevent, in averysimple and convenient way, the circulation of injurious currentsthrough the shaft contacting faces of the bearing.

motor, the particular form of motor indicated being of therepulsion-induction type, the brush shifting and commutatorshortcircuiting mechanism of which is shown.

The brush shiftin and short-circuiting mechanism illustrate being of acommon type, it will be only briefly described to explain how, in itsoperation, the motor shaft may become a part of a circuit including anarmature coil as the source of volta pro- 'ducing current through it.The brush holder 1 is slidably mounted on the hub 2 formed on the endplate 3 of the machine and is actuated to move the brushes into and outof contact with the commutator .4, by means of centrifugal elements (notshown) which, to move the brush holder to inoperative position, actuaterods 5 which bear against the gage t sleeve 6 on the shaft which in turnbears upon the on 7 having a flange projecting to enlie brush holder.The motion of the part described under the influence of centrifugalelements is opposed by the spring 8 which, when the centrifugal elementsare in retracted position during standstill or low speeds of themachine, moves the cu 7 to bring the brush holder back to position inwhich the brushes are in operative relation with the commutator. Thecollar 6 is provided with a circumferential groove in which lie a Ilurality ofrcommutatorshort-circuitmg 1e ements9; These elements moveoutand, engage the a commutator. segments. to

-t-short -"circuit-rthem." 'A lost motion conneci tion'be'tweenithe cup7. antl the brush holder is -:lprovi ded, as showngfin" order thatthe'shortzacrrcm-ting segments may: bemoved into op- "gpositioniwithrtheacommutator segments and 'short circujit them before v the brushes arelmoved out of contact with the commutator.

It frequently happens, however, that one or more of the=short-circuitingsegments will momentarilyqduring the transitional period between thestandstill position of the motor and the separation of the brushes fromthe commutator and, the complete short-circuit ing of the commutator, bein contact with The accompanying drawing-"illustrates one manner ofapplication of my invention. to a the commutator and directly, orthrough other elements, in contact with the metal collar 6 which slideson the motor shaft and employed to enclose the end of the bearing andshaft and have the contact portion of this element bear upon the centerof the end of the shaft. Since the dust cap is of conductive ma terialand, by threaded engagement with the bearin -housing, is in electricalconnection with t e bearing, the arrangement described forms anelectrical connection between the shaft and bearing other than thecontact faces of the bearing with the shaft'and one of much lowerresistance, whereby substantially none of any current through the shaftand end plate will pass through the bearing faces. By having the contactmember bear on the center of the shaft where the peripheral speed is thelowest, I avoid any substantial wear on the contact element.

The construction described has the further ward under the. influenceof-centrifugal force I v I advantage that the condition of the contactelement, contact faces, and the resiliency of the support can be readilyexamined and any defect removed. If the spring should be 5 broken orlose its temper the bypassing circuit can be restored by the simple andinexpensive expedient of substituting another cap with its attachedspring contact.

Having fully described my invention, what I claim as new and desire tosecureasLetters f Patent of the United States is: a 1. Means forestablishing electrical cont ,x nection between a shaft and its bearinother than through their contact faces, whic comprises a cap on thebearing-housing and enclosing the end of the shaft, and a contactelement resiliently mounted on the cap and engagng the shaft.

2. cans for establishing electrical connection between the shaft and itsbearing other than through their contact faces, which comprises a cap ofconductive material en- ClOSlIlg the end of the shaft and in electricalconnection with the bearing, said cap being provided with a springcontact member adagtcd to bear on the central part of the end of teshaft and electrically connect the shaft with the cap.

In testimony whereof, I hereunto affix my signature, this 23d dag ofJanuary, 1929.

SWEICHSEL.

